LEDs (light emitting diodes) have been used for various lighting purposes for many years, including, for example, as indicator lights and in arrays to form information displays. An LED is essentially a PN junction semiconductor diode that emits light when a current is applied thereto. The LED is a solid state device which operates at a low current and, as a single unit, produces negligible heat. It is typically encapsulated in a resin material which protects the device, making it durable and long-lasting. The use of conventional semiconductor light emitting diodes solves the problems of entrapped heat, lamp longevity, frequent lamp replacement and higher current operation. These structures thus possess the advantages over standard incandescent, fluorescent and HID (high intensity discharge) lamps by operating at relatively low voltages (e.g., in some cases as low as approximately three volts) and being relatively more energy efficient (e.g., generating approximately twenty-five lumens of light per watt). As is known, incandescent lamps are widely used in various existing lighting structures such as exit lights, flashing lights, hand-held signal lights (such as those used by traffic police), and display lights (such as those used in instrument panels), while fluorescent lamps are used in such lighting fixtures as office lighting, workshop lighting, and household lamps. HID lamps are used in a variety of environments, both indoors and outdoors, as well as in some automobile headlight systems.
Fluorescent, HID and incandescent lamps (especially incandescent lamps) are susceptible to vibration, which may cause a failure or a shortening of the useful life of the bulb. The mean failure time for a typical incandescent lamp product is less than about 2000 hours. In comparison, a fluorescent lamp will need replacement approximately every 15,000 hours and an HID lamp will need replacement about every 20,000 hours. Ballasts are also needed with respect to fluorescent lamps, which also typically need replacement within a fixed period, e.g., every five years. Such replacements are costly and disruptive to persons exposed to such lighting sources, particularly in a workplace environment such as a surgical or dental facility. In sharp contrast, LED lamps typically have a mean failure time of approximately 100,000 hours. Understandably, the use of LED as light sources thus presents many advantages over incandescent, fluorescent and HID lamps. This is especially true in the medical environment. LEDs can provide light in the desired 5000-5500K color temperature without the generation of excessive amounts of heat per LED. This is particularly true for the large majority of LEDs which do not produce light in the IR spectrum. For those LEDs which do produce light in the IR spectrum, heat generation is of course more of a concern. As known, heat is undesirable in such an environment. Although a typical single LED (one which does not produce light in the IR spectrum) produces relatively little heat, when utilized in combination with several others (especially when in close proximity thereto), an undesirable amount of heat may be generated when several such devices are used in close relationship to medical staff and/or a patient during relatively complex procedures as surgery or dental work. Excessive heat, for example, may rapidly dry exposed tissues of a surgical patient, which is of course undesirable. As understood from the teachings herein, the present invention is able to provide the many advantages of using multiple LEDs while assuring effective heat escape so as to assure excessive, undesirable heat does not affect nearby medical staff, patients and others who may be in close proximity to the invention.
As is also known, light produced from a single LED source is relatively concentrated, meaning that it appears to emanate from a small point source. A potential concern with such a characteristic is that metering units designed to measure the lamp's output may report that the lamp fails to meet required specifications. This is because such measurements are taken not only from the lamp's optical axis but over a broader range, e.g., plus or minus ten degrees from the lamp's axis. To accommodate for this, some lamps currently on the market include an array of several LEDs positioned on a suitable base so as to provide a much larger, but less concentrated output. As indicated from the foregoing, the present invention is able to successfully utilize several LEDs, and, as taught herein, does so while assuring optimal output in the intended environment and, significantly, while providing a substantially concentrated light output as is considered essential in medical environments such as mentioned above. As further indicated from the above, such features are provided from a multiple LED assembly and lamp using same in which heat is effectively allowed to escape and not adversely affect the lamp operators and others nearby. Such a product is considered to represent a significant advancement in the art.
The following U.S. Patents describe and illustrate various types of lighting products, most of these patents describing lighting assemblies utilizing one or more LED's as the light source. This listing is not an admission that any of said patents are prior art to the present invention.
In U.S. Pat. No. 7,128,444 there is described a light emitting diode lamp which includes a lead terminal formed with a cup having a conical inner circumferential surface serving as a light reflective surface, an LED chip bonded to a bottom surface of the cup with a die bonding material, and a molded portion made of a transparent synthetic resin for packaging the cup of the lead terminal.
In U.S. Pat. No. 7,086,767, there is described a solid-state (e.g., LED) light source compatible with existing sockets normally reserved for filamented lamps. The lamp may be formed with a hollow base formed to mechanically and electrically adapt to a socket. A circuit board substantially surrounds the base's metal core. A glass dome covers the sub-assembly after it is inserted into the hollow base and is sealed thereto.
In U.S. Pat. No. 7,070,304, there is described an LED which includes a substrate, a semi-spherical concave surface part formed in the substrate, and a transparent stage disposed in the semi-spherical concave surface part in the substrate. An LED chip is mounted on the horizontal upper surface of the transparent stage, a reflective member forms a truncated cone-shaped concave surface part disposed to be joined to an end of the semi-spherical concave surface part and attached on the substrate. A sealing body is disposed in the joined concave surface parts to cover the LED chip. The transparent stage includes a lower surface having a convex surface corresponding to a concave surface of the semi-spherical concave surface part and an upper surface formed in a horizontal surface.
In U.S. Pat. No. 7,066,626, there is described an LED lamp including a circuit substrate on which an electrode pattern is formed, a reflecting frame including a tapered concave portion having an inner peripheral surface broadening toward an upper end of the reflecting frame, a light emitting unit disposed on a central portion of the concave portion and including a plurality of LEDs, an air layer disposed above the light emitting unit, and a lens body provided through the air layer above the reflecting frame.
In U.S. Pat. No. 7,055,991, there is described a low-power, high-intensity lighting apparatus which includes a lamp base, a lamp housing, and a lamp unit. The lamp base includes a parabolic reflector. The lamp housing is mounted on the lamp base, and includes a surrounding wall and an optical condenser. The surrounding wall has a first open end, and a second open end opposite the first open end. The optical condenser is mounted on the lamp housing at the second open end. The lamp unit is mounted on the lamp base, extends into the lamp housing through the first open end of the surrounding wall, and generates light that propagates toward the parabolic reflector and that is reflected by the parabolic reflector toward the optical condenser. A plurality of LEDs may be used as the light source.
In U.S. Pat. No. 7,052,161, there is described an illuminative device essentially comprising a light source and a diffusing cover which is made of colored plastic. The light source consists of one or several light-emitting diodes (LEDs) emitting a colored and substantially monochromatic light. The diffusing cover assigned thereto has a transmission (DIN 5036) of at least 35% and a reflection (DIN 5036) of at least 15%, with the wavelength of the light-emitting diode operating at relative maximum energy.
In U.S. Pat. No. 7,040,779, there is described a lamp structure which the authors describe as being generally unbreakable. The lamp preferably is provided with a plurality of LEDs arranged with rows and columns on a circuit card or board and projecting upwardly in the same direction there-from. The lamp is constructed by encapsulating the board and LED arrangement in a moldable lens material.
In U.S. Pat. No. 6,994,455, there is described a plurality of LED lamp modules each of which includes a base, an LED drive circuitry mounted on the base, and a cover coupled with the base to cover the LED drive circuitry. The LED lamp modules are stacked one on another while a single flat cable is extended through the LED lamp modules so as to have at least one first portion disposed outside the LED lamp modules and a plurality of second portions disposed inside the LED lamp modules to be electrically connected to the LED drive circuitry in each of the LED lamp modules.
In U.S. Pat. No. 6,988,819, there is described a lamp assembly (e.g., automobile lamp) with an integrated LED support frame. An electrically conductive lead frame is encapsulated in between the interior and exterior surfaces of a housing. Surface mounted LED light sources and associated drive components are attached to the lead frame, and thus to the housing. A positive terminal and a negative terminal are formed from the lead frame on the inside to the outside of the housing, so that electricity may be transmitted from an external source to the LED light sources on the inside of the housing. The LED light sources are energized by the conductive lead frame formed into or onto the housing, thus eliminating the need for a separate printed circuit board with a conductive lead frame.
In U.S. Pat. No. 6,948,829, there is described a light emitting diode (LED) light bulb that includes plural individual elements as sub-assembly elements of the overall light bulb. Different sub-assembly elements of a lens, a LED printed circuit board, a housing also functioning as a heat sink, a lower housing, and other individual sub-assembly components are utilized. The LED printed circuit board sub-assembly containing the LEDs can also be provided relatively close to a base.
In U.S. Pat. No. 6,851,834, there is described a light fixture which consists of one or more LED packaging systems within a housing. Each LED packaging system includes one or more LED light sources that simultaneously shines onto opposing reflecting surfaces, then shines forward through encapsulation material. The housing consists of a cluster of prewired sockets with an outer reflective surface. Electrical wiring runs from the rear of the first socket and then to an adjacent socket in a daisy chain fashion. Each socket includes connectors configured to provide each LED packaging system with a source of electricity. The housing has diffusers that adjust the light to an evenly distributed appearance.
In U.S. Pat. No. 6,827,467, there is described an illuminating apparatus having a light source, an optical unit disposed on the object side of the light source having a lens portion having positive refractive power in the central portion thereof, incidence surfaces on which light from the light source is incident and reflecting surfaces for totally reflecting the incident light, on both sides of the lens portion, and an emergence surface from which the light reflected by the reflecting surfaces emerges. A beam emerging from the lens portion and a beam emerging from the emergence surface intersect with each other substantially at the same place in their condensed state. A second optical unit has a plurality of prism portions, wherein the relative interval between the optical unit and the second optical unit are changed to vary an irradiation angle.
In U.S. Pat. No. 6,793,374, there is described an LED lamp which has the appearance of a conventional incandescent lamp, this LED lamp including a gear column which is connected between a cap and substrates, all encased within an envelope (bulb). The substrates are arranged as a polyhedron with planar surfaces, with each surface having a plurality of LED's thereon. The polyhedron shape thus assures output in a variety of directions. The gear column also has a heat-dissipater, which interconnects the substrates and the lamp cap.
In U.S. Pat. No. 6,709,132, there is described an LED bulb with an intensity allegedly close to that of tungsten bulbs. The described “problem” in directivity of LED bulbs is allegedly solved. The LED bulb comprises a printed circuit board which is flat when developed and then bent to form a cage. A plurality of LEDs are disposed on the printed circuit board, and a transparent or semi-transparent cover encloses the board. The board may have a plurality of belt-like branches which extend in radial directions.
In U.S. Pat. No. 6,659,632, there is described an LED lamp which includes multiple LED members, a plane circuit board, an LED fixing cover, a circuit board mounting seat, a drive circuit, and an LED lamp base having a bulb copper head. The plane circuit board is initially cut to form a multiple-ring shape. Then, the multiple LED members are arranged and soldered on the plane circuit board. The circuit board mounting seat is next mounted on the bottom of the plane circuit board, thereby forming a spatial shape having a convex arcuate face. The plane circuit board and the circuit board mounting seat are next mounted in the LED lamp base. Then, the LED fixing cover is mounted on the LED lamp base.
In U.S. Pat. No. 6,657,382, there is described a light emitting device and display apparatus using a plurality of LEDs. The device has a light emitting chip and a first layer covering the light emitting chip. A second layer including a light scattering material is provided over the first layer, and the surface of second layer has a plurality of protrusions which follow the topology of the light scattering material. The display apparatus is formed by disposing these light emitting devices in an array on a substrate.
In U.S. Pat. No. 6,568,834, there is described a light modifying material composed of ethylene/butene-1 copolymer or propylene homopolymer or a combination of the two, and lighting devices using the material in a light transmitting cover. It is preferred that the light source for the devices is a semiconductor or light emitting diode (LED), to produce an energy efficient light source. The lamp may use a bayonet-type base.
In U.S. Pat. No. 6,527,419, there is described an illumination assembly consisting of a light source such as an LED that produces a near field image, and a means of imaging and focusing the near field image. The LED includes a chemical light emitting chip, a reflector cup and a phosphor coating over both the emitter chip and the reflector cup to produce an allegedly uniform, concentrated, high intensity near field image. The LED also has a clear housing having a narrow angle beam distribution. The means for imaging and focusing the near field image is a convex optical lens having a radius of curvature equal to twice the overall thickness of the lens. The optical lens is installed in fixed spaced relation to the LED such that the lens is imaging the reflector cup of the LED rather than the light on the surface clear LED housing.
In U.S. Pat. No. 6,507,290, there is described a light source in the form of an LED cluster module suitable for use as an aircraft forward position light source. The light source comprises multiple LED components mounted on a base structure together with supporting electronic components to regulate the function of the LED components. The LED components are configured on the base structure in a manner so as to be capable of complying with the Federal Aviation Regulations minimum light intensities or candela requirements and color specifications, while in a preferred implementation using a traditional aircraft 28-volt power supply.
In U.S. Pat. No. 6,328,456, there is described an LED lamp and method of using one or more lamps, and portable lighting products such as flashlights using such LED lamps. The LED lamp allegedly provides uniformly distributed light that radiates spherically approximately 270 degrees. The chip is encased in an envelope surrounding the chip, with the envelope extending from a first position below the position of the chip to a second position above the chip. The second position of the envelope forms a lens with the surface of the lens being configured and positioned relative to the chip such that a substantially uniform portion of light emitted from the chip is reflected off of the surface.
In U.S. Pat. No. 6,161,910, there is described an LED reading light assembly which includes an optical assembly, a circuit board, a housing, and a control system. The optical assembly includes a holographic lens and an LED assembly in which the circuit board has a plurality of LEDs disposed on the outward facing side thereof. The power circuit board provides a constant source of electric current to power the LEDs. The housing includes a housing plate disposed behind the LED circuit board and a black anodized fin plate. The control system includes a temperature protection circuit monitoring the ambient temperature at the LED assembly during operation and adjusting the power supplied to the LEDs to maintain the ambient temperature within a selected temperature range.
In U.S. Pat. No. 5,947,588, there is described an LED light bulb which can be used in conjunction with a conventional light fixture mounted to a vehicle. The light fixture includes a hollow lens and a base plate attached to the lens. The base plate has a conventional socket housing with one or more contacts which is electrically coupled to a power source. The LED light bulb comprises an electrical circuit board, a plurality of light-emitting diodes mounted to the circuit board and extending upwardly in a single direction, and a bayonet-type connection post attached to the circuit board and adapted to be connected to the socket housing.
In U.S. Pat. No. 5,931,570, there is described an LED lamp which consists of a light emitting bulb-shaped unit including an epoxy resin bulb-shaped portion; two leads (of which one end is extended outside the bulb-shaped portion and the other end is embedded in the bulb-shaped portion), and an LED chip connected to the ends of the two leads and embedded in the bulb-shaped portion. The surface of the bulb-shaped portion of the LED lamp is formed in an appropriate process to be either a frosted glass surface, a cut-diamond surface, a surface covered with small particles, or an optically-diffusing cap.
In U.S. Pat. No. 5,897,195, there is described an illuminator with a cylindrical or truncated-conical array of LEDs producing collimated light beams that are directed onto axially-spaced, inclined surfaces formed on the outer periphery of a hollow, similarly shaped (i.e., cylindrical or truncated-conically shaped) Fresnel-like diffuser which refracts and directs rings of light beams onto the surface of a workpiece at angles of incidence ranging anywhere from fifteen to eighty degrees. The array of LEDs is surrounded by a circuit board which supplies power selectively to illuminate the LEDs. The Fresnel-like diffusers have in the outer peripheral surfaces thereof circumferential grooves forming annular, prism-shaped projections which differ in shape depending upon the desired angle of incidence of the light beams that are to be projected.
In U.S. Pat. No. 5,879,076, there is described a method and apparatus for light transmission adapted for use in a reflective belt, safety vest, or similar devices requiring visibility of a bright and/or reflective material where a light source of one or more lighting elements (e.g., LEDs) is positioned to transmit light along a self-supporting elongated light transmitting member of a hot-melt adhesive thermoplastic material. A flashing circuit for the light source includes a battery pack convertible to direct current voltage.
In U.S. Pat. No. 5,865,529, there is described an LED lamp which allegedly allows a 360 degree viewing angle in a horizontal plane about its central vertical axis, as well as, a 360 degree viewing angle about the vertical circle. The lamp utilizes a concave lens to establish a focal point within the envelope to re-radiate the radiant energy.
In U.S. Pat. No. 5,808,718, there is described an LED print head is for use in an LED printer. The LED print head has an LED circuit board on which a plurality of LED chips are mounted in line, and a lens assembly having rod lenses for focusing light emitted from the LED chips on a surface of a photosensitive drum in the LED printer. A first member or slider engages either the LED circuit board or the lens assembly and is adapted to displace stepwise to cause either the LED circuit board or the lens assembly to flex stepwise relative to the surface of the photosensitive drum. A second member or slider engages said first member to movably hold said first member. The LED circuit board or lens assembly is flexed so that a point on the photosensitive drum and the surface of the corresponding LED form a pair of conjugate points with respect to the corresponding rod lens.
In U.S. Pat. No. 5,528,474, there is described lamp, such as for truck trailers and/or tractors, which is provided with LEDs mounted to a circuit board placed in a housing. The LED's and circuit boards are fully embedded in a resin material cured with thermally conductive particles suspended therein for conducting excess heat to the outer aluminum housing and the outer environment. The lens cover has a series of parallel, elongated lens ribs providing constant optics while allowing additional LEDs to be positioned in a row behind a lens rib. The LED circuit board has large traces to enhance heat dissipation.
In U.S. Pat. No. 5,313,729, there is described an LED display unit comprising a printed circuit board with a plurality of LEDs on the board. Parts of the LED, except for light emitting sections thereof, are sealed by a resin. The LEDs having the portions thereof sealed by the resin are oriented in a case, with the cases being arranged on an attaching plate to form a large-sized display panel. The case has a rear face thereof which is brought to a configuration in which spaces exist between the attaching plate and portions of the case.
In U.S. Pat. No. 5,221,140, there is described a sub-miniature lamp in which a lamp body having a filament and an envelope is covered with a soft silicone rubber cap of a predetermined color having an opening at one end to a predetermined length of lead wires extending from the lamp body. A closure member is fitted to the opening of the envelope to seal the opening. The colored silicone rubber cap covers the envelope of the lamp body and is extended to a predetermined length of the lead wires, with the opened end of the cap fitted with an adhesive agent or a disc pad.
In U.S. Pat. No. 5,121,311, there is described an LED holder which uses two pivotably connected portions to mount an upper and a lower LED on a printed circuit board. The first portion has a pair of receptacles for holding the bodies of the LEDs, and a pair of bores extending from the bottom of each receptacle. The second portion has a pair of bores for receiving the leads of the top LED when the second portion is in an open position with respect to the first portion. Pivoting the second portion toward the first portion bends the leads of the top LED between the bores, and brings a guide surface to bear on the leads of the bottom LED, bending the bottom LED leads. Further pivoting the second portion latches it into place against the first portion, and holds the bent leads in position for connecting to a printed circuit board.
In U.S. Pat. No. 4,967,330, there is described an LED lamp having a generally hollow cylindrical encasement having at least one opening therein allowing gases and fluids exterior to the encasement to freely circulate within the interior thereof for cooling purposes. Embodiments include those wherein the encasement is screw-threaded and/or divided into sections with differing diameters.
In U.S. Pat. No. 4,929,866, there is described an LED automobile, e.g., tail light, lamp comprising a window through which light is released forwardly, a plurality of LEDs located at a corner of the window or behind the frame of the window, and a light reflector having a plurality of light reflecting faces whereby light emitted from the LEDs is reflected toward the window.
In U.S. Pat. No. 4,630,183, there is described an LED lamp and a method for producing thereof, in which at least one LED is connected between at least a pair of conductive members at the upper end portions thereof, the LED being embedded together with the conductive members in a molding of a light transmissible resin material, with the respective lower end portions of the conductive members being left exposed, and the respective exposed lower end portions of the conductive members being connected to a lamp base or cap. A contact member supports the lower end of the lamp base or cap and is insulated from the lamp base or cap.
In U.S. Pat. No. 4,580,196, there is described an arrangement for changing the illumination in an aircraft cockpit or other enclosure to a spectrum compatible with night vision infrared equipment. Selected LED elements are employed in multiple element arrays using a tether connected package that can be excited directly from existing wiring in fixtures.
In U.S. Pat. No. 4,559,589, there is described a lighting fixture including an enclosure, means disposed in the enclosure for supplying a central source of light therein, and a concave, generally parabolic reflector for directing a main beam of light out of the enclosure from the source generally along a given optical axis. The central source of light is located at the focal region of the concave reflector, the concave reflector includes a light penetrable region disposed at one side of the optical axis in a horizontal plane in common with the central light source, and the light-penetrable region forms an escape window out of the enclosure for part of the light from the source.
In U.S. Pat. No. 4,555,749, there is described a tie-bar of variable length for mechanically linking a desired number of lamps (such as LEDs) which includes dove-tailed channels with a “v-shaped” groove in each dove-tail channel. Each lamp is disposed in a housing having a compatible dove-tailed mounting channel designed to fit half of adjacent tie-bar channels on the tie-bar assembly. The “v-shaped” grooves are used to break the tie-bar to a desired length for mounting a required number of lamp housings.
In U.S. Pat. No. 4,329,737, there is described an LED arrangement with a light-emitting diode that is light-transmissive in an axial direction of the type used in examining instruments. The LED serves as a constant light source in conjunction with a diffusion disk, such as for fixation point stimuli, while the disk also serves as a stimulus that is lit by an additional, switchable light source, such as an incandescent lamp. Light from the incandescent lamp is transmitted through a light guide, such as an optical fiber, and through the light-emitting diode to the disk. A color filter is arranged between the additional light source and the light-emitting diode and both the additional light source and light-emitting diode are axially displaceable relative to the diffusion disk so as to enable adjustment of the respective luminous densities.
In U.S. Pat. No. 4,296,460, there is described a battery-powered lamp having a box-like casing with a top and side walls for housing at least one battery. At least one of the side walls has a depression which provides a generally planar depressed portion having an opening there-through. A light source is supported in the casing. A lens, through which light from the light source can be transmitted, has a peripheral rim which is a friction fit in the opening. On its peripheral rim is a plurality of ratchet-like teeth mutually spaced. These make snap fits with and locate behind the material of the side wall bounding the opening so as to resist lens removal. Outside the peripheral rim of the lens is a surrounding flange which limits the depth of insertion of the lens in its opening. The side wall bounding the opening has a plurality of spaced notches which register with the lens teeth to prevent rotation of the lens relative to the opening. The lens teeth are triangular in configuration and are integral with the lens rim. Two opposite side walls each has a depression in which an opening is disposed. The lens is a friction fit in each of the openings.
In U.S. Pat. No. 4,270,162, there is described a beacon lamp which includes a point source of light located surrounded by a transparent cap which is in the shape of a solid of revolution about an axis which forms at least one annular lens. The profiles of the optical surfaces of the lenses are such that these produce a cap which can be molded and which concentrates much of the light.
In U.S. Pat. No. 4,253,135, there is described a lamp having a central core that provides up to four faces for the support of illuminating units. The central core is made of four elongated, square core members which are spaced from each other by interfitting cross members to which the base and top plates of the illuminating units are secured. The complete lamps may be mounted one above the other, suspended on a chain, or supported on a base or pedestal to provide illumination. Each illuminating unit has a socket which supports a bulb which is enclosed between bottom and top plates by a U-shaped translucent element.
In U.S. Pat. No. 4,075,471, there is described a lamp assembly having a housing of which part defines a parabolic or paraboloidal mirror and part defines part of an ellipsoidal reflector. A lamp filament is mounted at the inner focal point of the reflector and the focal point of the mirror coincides with the outer focal point of the reflector. The housing has a lens element defining a window through which light is directed from the mirror. In one embodiment, an additional mirror and lens element are provided for receiving light from the reflector with the additional mirror directing the light in the opposite direction to the light directed by the first mirror. Further mirrors may be provided for increasing the horizontal spread of light.
As defined herein, the present invention represents an improvement in LED lamp design by providing an LED lighting assembly adapted for use in a lamp which may accommodate several such assemblies in order to provide a concentrated light output of desired intensity while assuring effective heat removal from the several closely positioned LEDs. The invention is thus ideally suited for use within a demanding environment such as during surgical and dental procedures, while still assuring a safe product. As defined herein, the invention may be produced using many conventional PCB technologies to thus assure a finished assembly of relatively low cost for a product having such capabilities It is believed that such a lighting assembly and corresponding lamp will constitute significant advancements in the art.